Individual study: Arthropod numbers and species richness increased with a reduction in management intensity within two arable farms in Germany

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Buchs W., Harenberg A. & Zimmermann J. (1997) The invertebrate ecology of farmland as a mirror of the intensity of the impact of man? An approach to interpreting results of field experiments carried out in different crop management intensities of a sugar beet and an oil seed rape rotation including set-aside. Biological Agriculture & Horticulture, 15, 83-107

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A small, controlled study of an arable and set-aside field on a farm near Braunschweig, Germany (Buchs et al. 1997) found that arthropod numbers and species richness tended to increase with a reduction in management intensity. More species of spider were found in set-aside than arable plots with four levels of management intensity (set-aside: 33-36; reduced intensity: 10-22; conventional: 11-13). The effect on spider abundance was less clear. Set-aside also had a greater density of wolf spiders (Lycosidae; set-aside: 68/trap; arable 10-22) and a lower proportion of pioneer species (set-aside: 8%; reduced inputs: 49-75%; conventional: 81%). Beneficial species, such as Carabus auratus, were more abundant in set-aside (97-148/trap) than arable plots (1-18/trap); their activity periods were also longer in set-aside. Similar effects were seen for juvenile spider abundance (set-aside: 108/trap; reduced intensity: 50-55; conventional farming: 21). In 1992-1995 a long-term set-aside was compared with four plots within an arable field that differed in the input of fertilisers and pesticides (high, 30-50% reduced, none), crop rotation (three/four course), tillage, weed control (mechanical/chemical), cultivars, drilling technique and catch crops. Six to eight emergence traps and pitfall traps sampled arthropods within each treatment. Traps were collected every 2-4 weeks throughout the year. Results for pest species are not included here.

A small, controlled study of three arable fields on two farms near Braunschweig, Germany (Büchs et al. 1997) found that arthropod numbers and species richness tended to increase with a reduction in management intensity, largely a reduction in fertilizer and pesticide inputs. Arthropod abundance, number of spider (Araneae) species, numbers of juvenile spiders, abundance and number of ladybird (Coccinellidae) species increased with a reduction in inputs. Abundance of beneficial species and length of their activity period also tended to increase with decreased fertilizer and pesticides. Specific species differed in their response to treatment and the intensity of effects depended on type of lifecycle. Reduced inputs increased the activity density of wolf spiders (Lycosidae) and decreased the proportion of pioneer species. Spider species with a wide range of ecological living conditions tended to increase with an increase in pesticides. In 1989-1992 four plots within an arable field received different management intensities: no fertilizers/pesticides, extensive or integrated cultivation with medium fertilizer/pesticide inputs and intensive cultivation with high fertilizer/pesticide inputs. In 1992-1995 four plots within an arable field received farming regimes that differed in the input of fertilizers and pesticides (high input, 30-50% reduction, none), crop rotation (three/four course), tillage, weed control (mechanical/chemical), cultivars, drilling technique and catch crops. A long-term set-aside was also sampled. Six to eight emergence traps and pitfall traps sampled arthropods within each treatment. Traps were collected every 2-4 weeks throughout the year. Results for pest species are not included here.